Additional Information

Sample collection sites will be set up using a grid system within sections to ensure spacing of sampling. Within each section, grid points will be randomly chosen for sampling. At least 30 surficial sampling sites will be chosen. Surficial sampling will be done by digging small holes that are 50-100cm deep, and then coring from 1m to 2 m. Samples will be collected from 0- 25cm, 25-50cm, 50-100cm, 100-150cm, and 150-200cm. In areas where the soil is coarse textured (cobbles and gravel), samples will be collected using pits to as close as 2 m deep as possible. Soil bulk density samples will also be collected while collecting samples for carbon analysis.

Access to deeper sediments is more difficult as deep coring is not feasible. Sampling will be done by accessing sideslopes that are open and accessible from the eroded sediments. At least 20 locations will be chosen for deep sampling. At these sites, samples will be collected from the sideslope every 1m after the top 2 meters to the deepest possible depth. Samples will also be collected for bulk density.

Carbon is also stored in coarse woody debris in the reservoir, namely with logs. Carbon stored in woody debris will be measured by first estimating the volume of the log using diameter and length measures and taking samples of the wood for analyses. C analysis will be done on all samples following drying using a CHN analyzer (Perkin-Elmer). While it is most likely that all of the carbon in the sediments is organic carbon, samples will be tested to determine if any carbonate carbon is present. If carbonates are found, these will be measured separately by analyzing samples before and after treatment to remove carbonates.

Sediment samples will be analyzed through a geographic information system (GIS) to better understand the organic carbon distribution through vertical and horizontal space in a reservoir setting. This will primarily involve the use of interpolation statistics to visualize carbon concentration within a spatial context. Sample sites will be assigned x, y coordinates and will also be given a Z value which will represent carbon content. For each core, coordinate will be taken using a high-accuracy GPS device which will allow for accurate mapping of samples. Once all data is collected and input, kriging—a common geostatistical interpolation tool—will be used within ESRI’s ArcGIS 10.1 software package. This technique will be utilized for its power to calculate values between sample points when distance and direction are assumed to reflect spatial correlation. This information, in turn, can be used to explain variation in the surface from one known point to the next, thus producing a comprehensive sediment carbon map of the drained reservoir at differing depths.

In addition to mapping carbon, we will estimate the total carbon stored in the sediments using the concentrations, depth measurements, grid area and bulk densities. This total storage of carbon in the sediment pool will be a unique measure that can be used to estimate future carbon transfer to the ocean by erosion, and can serve as a baseline to measure other carbon fluxes.

One carbon flux from the reservoir sediments that could be significant is gaseous losses of carbon. We propose to do some preliminary sampling of gaseous losses of carbon from the sediments. Twelve small rings will be pounded into the sediments at locations that cannot be easily accessed by the public so that rings can remain in place. Each ring will be sealed along the outer edge. Sleeves will fitted over these rings that can also be sealed using putty. A flat plexiglass plate containing a septum will be attached to the top of the sleeve to form a cylindrical chamber. These chambers will be places on the rings for a 24 hr period once a month. Samples will be collected at the end of the 24 hr period using a gas tight syringe and returned to the lab for analysis using a gas chromatograph. With a know time period, specific chamber volume, soil surface area, and concentration of gas, the flux of gas from the soil can be determined. This preliminary data will be used to estimate the relative importance of gaseous losses of carbon. Possible future work could examine the accumulation of carbon within the soil/sediments and the accumulation of carbon in vegetation.